#include <stdlib.h>
#include <stdio.h>
#include <sys/epoll.h>

int main(int argc, char const *argv[])
{
#if 1
    char character;
    scanf("%c", &character);

    if (character < 'A' || character > 'z')
    {
        printf("输入字符不合法\n");
        return EXIT_FAILURE;
    }

    if (character < 'a')
    {
        printf("转换前的字符为 %c,转换后的字符为 %c\n", character, character + 32);
    }
    else if (character >= 'A')
    {
        printf("转换前的字符为 %c, 转换后的字符为 %c\n", character, character - 32);
    }
    else
    {
        printf("输入的值为数字 %c", character);
    }

#endif

    return 0;
}
